Several lines of evidence indicate that dietary taurine can reduce hypertension in humans and in animal models. Taurine (2-aminoethanesulfonic acid) is a non-protein, free amino acid found in many tissues particularly brain, myocardium, liver, muscle, and kidney. In the SHR on either a high or basal NaCl diet, sympathetic blockade greatly decreases arterial pressure rhythm, suggesting that the sympathetic nervous system contributes significantly to SHR hypertension, especially during its development. In addition, in SHR, high NaCl diets significantly increase daytime arterial pressure after a week of feeding, but they have little effect at that time point on daytime arterial pressures of normotensive WKY. This is especially evident after four nights of high NaCl treatment. Further, high NaCl diets initially increase arterial pressure in the nighttime and more slowly increase daytime arterial pressure in both SHR and Wistar Kyoto rats (WKY a normotensive control for SHR). However, in adult SHR compared to other strains, arterial pressure declines slowly in the morning (as the animals begin to sleep) and remains in the hypertensive range throughout the sleep period (mean arterial pressure > 110 mmHg). Spontaneously hypertensive rats (SHR) display a circadian rhythm that is directly correlated with activity. In contrast, during the development of hypertension, the arterial pressure amplitude is typically greater than normal. Established hypertension is associated with decreased amplitude of diurnal arterial pressure variation, in that arterial pressure fails to decrease in the non-active period ( e.g., sleep), especially in older adults. In contrast, rats are generally nocturnal animals, and thus their diurnal rhythm is reversed, i.e., their arterial pressures are elevated at night during active behavior, and decreased during the daytime. Thus, in humans, arterial pressure typically increases during the daytime and decreases during the nighttime. Arterial blood pressure displays a diurnal variation, i.e., it is elevated during active behavior periods and decreased during quiescent periods ( e.g., sleep). Hypertension is a risk factor for both acute and chronic adverse diseases, including stroke and cardiovascular disease. This review considers both the positive and negative effects of taurine on blood pressure in animal models and their applications for human interventions. Differences in techniques for measuring arterial pressure, duration of treatment, and animal models likely affect the response in different studies. In humans, some epidemiologic studies indicate that people with high taurine and low salt diets display lower arterial pressure than those with low taurine and high salt diets. Further, other consideration may play a role, e.g., taurine supplementation improves hypertension in spontaneously hypertensive rats on a low salt diet but fails to attenuate hypertension on a high salt diet. One reason for the inconclusive nature of past studies may be that taurine having both positive and negative effects on cardiovascular system depending on when it is assessed, some effects may occur early, while others only appear later. Though several lines of evidence indicate that dietary taurine can reduce hypertension in humans and in animal models, evidence that taurine supplementation reduces hypertension in humans has not been conclusive. It plays several physiological roles including cardiac contraction, antioxidation, and blunting of hypertension. Taurine (2-aminoethanesulfonic acid) is a β-amino acid found in many tissues particularly brain, myocardium, and kidney.
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